Process for production of oriented silicon steel

Claim 2

In a process for producing oriented silicon steel having improved core loss and magnetic permeability in the rolling direction, comprising the steps of hot rolling a steel containing up to about 0.07% carbon, about 2.7% to about 3.3% silicon, about 0.05% to about 0.15% manganese, about 0.02% to about 0.035% sulfur and/or selenium, about 0.024% to about 0.040% total aluminum, about 0.0050% to about 0.0090% nitrogen, and balance essentially iron, subjecting the hot rolled steel to an initial anneal, cooling the steel, water quenching to a temperature below about 400° C. in less than about 200 seconds, cold rolling to final thickness, decarburizing the steel, applying an annealing separator, and subjecting the steel to a final anneal in a reducing atmosphere, the improvement which comprises varying the temperature of said initial anneal within the range of from about 1040° to less than about 1115° C. and the temperature at which said water quenching is started within the range of from about 700° to less than about 870° C. when the total aluminum and nitrogen contents are to the right of and below the straight lines defined by percent nitrogen=0.0090% and percent nitrogen=0.83×percent aluminum-0.022% in FIG. 2 herein, and varying the temperature of said initial anneal within the range of from greater than about 1115° to about 1175° C. and the temperature at which said water quenching is started within the range of greater than about 870° to about 1090° C. when the total aluminum and nitrogen contents are to the left of and above the straight lines defined by percent nitrogen=0.0060% and percent nitrogen=0.83×percent aluminum-0.0184% in FIG. 2 herein.

Claim 3

The improvement claimed in claim 1, wherein said hot rolled steel is water quenched after said initial anneal to a temperature below about 400° C. in from 10 to 50 seconds.

Claim 4

The improvement claimed in claim 1, wherein said initial anneal is a continuous anneal, with a soaking time ranging from about 30 seconds to about 3 minutes.

Claim 5

A process for producing oriented silicon steel having improved core loss and magnetic permeability, comprising the steps of hot rolling a steel containing up to 0.07% carbon, about 2.7% to about 3.3% silicon, about 0.05% to about 0.15% manganese, about 0.02% to about 0.035% sulfur and/or selenium, about 0.024% to about 0.040% total aluminum, about 0.0050% to about 0.0090% nitrogen, and balance essentially iron; subjecting the hot rolled steel to an initial anneal; cooling the steel; water quenching to a temperature below about 400° C. in less than about 200 seconds; the temperature of said initial anneal being varied within the range of from about 1040° to less than about 1115° C. and the temperature at which said water quenching is started being varied within the range of from about 700° to less than about 870° C. when the total aluminum and nitrogen contents are to the right of and below the straight lines defined by percent nitrogen=0.0090% and percent nitrogen=0.83×percent aluminum-0.022% in FIG. 2 herein, and the temperature of said initial anneal being varied within the range of from greater than about 1115° to about 1175° C. and the temperature at which said water quenching is started being varied within the range of from greater than about 870° to about 1090° C. when the total aluminum and nitrogen contents are to the left of and above the straight lines defined by percent nitrogen=0.0060% and percent nitrogen=0.83×percent aluminum-0.0184% in FIG. 2 herein; cold rolling to final thickness in at least one stage of cold reduction; decarburizing the steel; applying an annealing separator; and subjecting the steel to a final anneal in a reducing atmosphere at a temperature of at least about 1090° C.

Claim 6

A process for producing oriented silicon steel having improved core loss and magnetic permeability, comprising the steps of hot rolling a steel containing up to 0.07% carbon, about 2.7% to about 3.3% silicon, about 0.05% to about 0.15% manganese, about 0.02% to about 0.035% sulfur and/or selenium, about 0.024% to about 0.040% total aluminum, about 0.0050% to about 0.0090% nitrogen, and balance essentially iron; subjecting the hot rolled steel to an initial anneal; cooling the steel; water quenching to a temperature below about 400° C. in less than about 200 seconds; the temperature of said initial anneal being varied within the range of from about 1040° to less than about 1115° C. and the temperature at which said water quenching is started being varied within the range of from about 700° to less than about 870° C. when the total aluminum and nitrogen contents are to the right of and below the straight lines defined by percent nitrogen=0.0090% and percent nitrogen=0.83×percent aluminum-0.022% in FIG. 2 herein, and the temperature of said initial anneal being varied within the range of from greater than about 1115° to about 1175° C. and the temperature at which said water quenching is started being varied within the range of from greater than about 870° to about 1090° C. when the total aluminum and nitrogen contents are to the left of and above the straight lines defined by percent nitrogen=0.0060% and percent nitrogen=0.83×percent aluminum-0.0184% in FIG. 2 herein; cold rolling to final thickness in at least one stage of cold reduction; decarburizing the steel; applying an annealing separator; and subjecting the steel to a final anneal in a reducing atmosphere at a temperature of at least about 1090° C.